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Comment by dozzie | Hacker News Reader

Then you don't have "Erlang-like actors", which is an implementation of CSP (unintended, designed separately, but still).

Unless you mean that some data is shared, but cannot be modified, but this would be semantically identical to not sharing anything.

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Shared immutable data is one option, but what I also mean is that when the type system can guarantee at compile time that the actor sending the data does not have read- or write- access to the data after sending, the system knows it can just "recycle" the old data, without run-time overhead.

Look, just read up on the type system, specifically reference capabilities[0]. It's basically what allows for safe mutability and data passing when required.

[0] https://tutorial.ponylang.org/capabilities/reference-capabil...

>Unless you mean that some data is shared, but cannot be modified, but this would be semantically identical to not sharing anything.

That's the gist of Rust's borrow checker. Shared data can't be modified (unless you use a Mutex or something similar, but then you need to acquire a lock, so data you can mutate is not shared).

Erlang puts all binary data on a heap which is shared between actors

I said already:

> [...] this would be semantically identical to not sharing anything.

Erlang's data sharing (and no, not all binary data, just over a certain threshold; if you want to nitpick, be diligent and precise) is merely optimization trick, highly uninteresting when it comes to discussing type systems (because its semantics are identical to not sharing anything at all).

BTW, if you talk about Erlang, use proper Erlang's terminology. Erlang doesn't have "actors", it has "processes".

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